1. Field of the Invention
This invention is related to the method and device for oil water separation by coarse particulation or coalescence of the oil contents to separate oil effectively from such oil holding water including finely divided and scattered oil or oil in an emulsion state.
2. Description of the Prior Art
Conventional methods of oil separation from oil holding water include a gravity separation method, filtration method, adsorption method, cohesion disposition method, air floating method, microbiological process, electrolytic method, physical chemistry method and a coalescing or coarse particulating method.
The gravity method can only be applicable for coarse oil particles, and not for the separation of finely divided oil while the filtration method easily causes clogging, and requires large equipment for the back flushing process which is also difficult to prevent from clogging completely. The air floating method also requires a large system and makes it impossible to separate finely divided oil. The microbiological method requires large equipment and a long processing time, and the electrolytic or physical chemistry method is accompanied by secondary processing so as to result in problems of larger installation and complicated processing. Further, the normal type coarse particulation method is an ideal method but, however, cannot be applied for the range of emulsion type particles of a dimension smaller than 10.mu. except for precision filtration or ultrafiltration. The ultrafiltration can only be used for specific cases, because the equipment is large and expensive and the running cost is also high. On the other hand, an adsorbent, depending on its lipophilic nature, is expensive and a great deal of manpower is required for replacing it at a saturating point based upon to its adsorption limit being a major drawback due the impediment of oil film in the case of high oil concentration and high viscosity oil. The method of using an adsorbent as coarse particulation of smaller than 10.mu. oil particle content is impossible, and therefore this method is not adequate for the separation of emulsified materials. No practical small equipment for economically performing coarse particulating separation in the range of oil content with smaller than 10.mu. particles is available at the present time.